1. Field of the Invention
The presently disclosed subject matter relates to an endoscope, and more particularly, to an endoscope in which an observation window can be cleaned by jetting a cleaning fluid from a nozzle.
2. Description of the Related Art
In general, an endoscope for medical use is provided with a nozzle for cleaning an observation window, and the observation window can be cleaned as needed by jetting a cleaning liquid from the nozzle.
However, when the observation window is cleaned by jetting the cleaning liquid from the nozzle in this way, the cleaning liquid attaches onto the observation window to block the field of view of the observation window in some cases. Therefore, in the endoscope for medical use, the cleaning liquid and air can be selectively jetted from the nozzle, and the air is jetted after the cleaning liquid is jetted, whereby the cleaning liquid attaching on the observation window can be blown away by the air to be removed.
However, the air is jetted only in a given direction, and hence the air does not reach the cleaning liquid depending on an attachment position of the cleaning liquid, so that the cleaning liquid cannot be completely removed in some cases.
Japanese Patent Application Laid-Open No. 2007-202836 describes that, in order to let the cleaning liquid drain off to a higher level, a suction port is placed in the vicinity of an observation window farther from the nozzle, of two observation windows.
In addition, Japanese Patent Application Laid-Open No. 2005-168770 describes that an illumination window is formed so as to be inclined in a manner that an optical axis of an illumination optical system is inclined.
Further, Japanese Patent Application Laid-Open No. 2004-254729 describes an endoscope including a distal end part to which a cap is detachably attached, in which a joining portion between an end part of the cap and an end part of a distal end part main body is formed so as to have a continuous curved surface.
In addition, Japanese Patent Application Laid-Open Nos. 2006-314459, 2006-320366, 2006-320367, and 2008-86664 each describe that an end surface of the distal end part on which the observation window is placed is formed in a stepwise manner, an inclined surface is formed in a wall part between respective adjacent two steps, and the cleaning liquid is jetted from the cleaning nozzle toward the inclined surfaces.